The invention relates to telecommunications and more particularly to redundant interfaces for telecommunications in the Signaling System 7 network.
In telecommunications systems, data are transmitted between endpoints. Endpoints include, e.g., telephones (including cellular phones), voicemail systems, fax machines, email addresses, and computers.
During transit, the data are processed through various apparatus according to protocols and/or techniques and/or guidelines for switching the data among system components. One such signaling system is called the Signal System #7 (SS7). SS7 implements portions of the International Organization for Standardization (ISO) Open System Interconnection (OSI) seven layer protocol model.
Reliability of data transmission is important for telecommunications systems. Users of telecommunications systems need the data to be transmitted accurately and quickly (e.g., for faxes and telephone conversations). Thus, it is desirable to help ensure that failures in the telecommunications systems do not result in significant losses of data or time to transmit data.
The Signaling System 7 (SS7) network is a packet-based data network used worldwide to support the signaling requirements of modern telecommunications networks. The SS7 network interconnects various pieces of equipment used to provide telecommunications services. Examples of the services supported by the SS7 network include call supervision signaling for the support of local, long-distance, and international calling, signaling for the support of registration, inter-cell handoff, and roaming in wireless (cellular) networks, and transaction-based signaling for the support of enhanced services such as network voicemail, free phone (800-number) calling, caller ID display, pre-paid calling cards, and local number portability.
The SS7 network includes a set of equipment nodes interconnected by sets of signaling data links. The equipment nodes can be classified as either signal transfer points (STPs) or signaling end points (SEPs). The STPs are switches or routers that provide for reliable transfer of signaling packets, or messages, between the SEPs. The SEPs implement the actual telecommunications services described above. Typical signaling end points are telephone switching systems (e.g. Service Switching Points (SSPs)), mobile switching centers (in cellular networks), service nodes (SNs) providing enhanced voice services, database systems holding subscriber information, Intelligent Peripherals (IPs), and Service Control Points (SCPs).
In order to meet the service availability goals for telecommunications equipment/service providers, or in some cases to meet regulatory requirements, stringent reliability requirements are placed on the SS7 network. Signaling nodes must be designed for up to 99.999% availability, equating to less than 6 minutes of down time per year. Each SEP is typically connected to at least 2 STPs, using groups of redundant signaling links that share the traffic load, to guard against the failure of a single signaling link, or even an entire STP, from causing a complete service outage.
In general, in an aspect, the invention provides a signaling system 7 (SS7) processing system for use in an SS7 network. The system includes a primary interface configured to process communications according to at least one layer of the SS7 protocol stack, the primary interface being configured to provide checkpoint messages relating to the communications and the at least one layer of the SS7 protocol stack, each layer of the at least one layer of the SS7 protocol stack having a corresponding set of information associated with each communication, and a backup interface configured to process communications according to the at least one layer of the SS7 protocol stack, the backup interface being coupled to the primary interface, and configured, to receive the checkpoint messages from the primary interface, wherein the checkpoint messages contain sufficient information for the backup interface to properly process communications that are transferred from being processed by the primary interface to being processed by the backup interface and contain less than all information in each set of information associated with each of the communications corresponding to the at least one layer of the SS7 protocol stack.
Implementations of the invention may include one or more of the following features. The primary interface and the backup interface are each configured to process communications according to at least two layers of the SS7 protocol stack. The primary interface and the backup interface are each configured to process communications according to message transfer part 3 (MTP-3), signaling connection control part (SCCP), integrated services digital network user part/telephone user part (ISUP/TUP), and transaction capabilities application part (TCAP) layers of the SS7 protocol stack. The backup interface is configured to initialize the MTP-3, SCCP, ISUP/TUP, and TCAP layers to default conditions. The backup interface is configured to request update checkpoint messages from the primary interface to alter the MTP-3, SCCP, ISUP/TUP, and TCAP layers of the backup interface from the default conditions. The backup interface is configured such that the MTP-3, SCCP, ISUP/TUP, and TCAP layers of the backup interface independently request the update checkpoint messages from corresponding layers of the primary interface. The backup interface is configured to request the update checkpoint messages in response to the backup interface being restored to service. The primary interface is configured to provide the update checkpoint messages intermixed with normal-operation checkpoint messages.
Implementations of the invention may also include one or more of the following features. The checkpoint messages contain only information sufficient for the backup interface to properly process communications that are transferred from being processed by the primary interface to being processed by the backup interface. The at least one layer includes a message transfer part 3 (MTP-3) layer and wherein the primary interface is configured to provide a first MTP-3 checkpoint message portion, of a checkpoint message, consisting of a link number and a new link state associated with a signaling link over which the associated communication is transferred in response to the signaling link changing states, and wherein the primary interface is configured to provide a second MTP-3 checkpoint message portion, of a checkpoint message, consisting of an address of a destination signaling point in the SS7 network and an address of a signal transfer point adjacent to the destination signaling point in response to at least one of accessibility of and a preferred route to the destination signaling point changing. The at least one layer includes a message transfer part (MTP) and a signaling connection control part (SCCP) layer and wherein the primary interface is configured to provide, in response to changes in status of the SS7 network, and SCCP network-status checkpoint message portion, of a checkpoint message, checkpointing MTP-pause and MTP-resume local to the primary interface in the SS7 network, SSA and SSP remote from the primary interface in the SS7 network, and subsystem in-service and subsystem out-of-service requests from an application local to the primary interface in the SS7 network. The at least one layer includes a signaling connection control part (SCCP) layer and wherein the primary interface is configured to provide, in response to a communication connection being confirmed or released, an SCCP connection checkpoint message portion, of a checkpoint message, including calling and called SCCP addresses, connection direction, connection service class, source and destination local references, SLS value, and identity of an application local to the primary interface in the SS7 network. The at least one layer includes a transaction capabilities application part (TCAP) layer and wherein the primary interface is configured to provide a TCAP checkpoint message portion, of a checkpoint message, to replicate states of open transactions in the backup interface. The TCAP checkpoint message portion consists of, in response to a call being initiated, source transaction identity, destination transaction identity, transaction state, source address, and destination address.
Implementations of the invention may also include one or more of the following features. The TCAP checkpoint message portion consists of, after a call has been initiated, transaction identity. The primary and backup interfaces are disposed in a common computer chassis. The primary and backup interfaces are disposed in separate computer chassis. The backup is configured to assume processing of communications previously being processed by the primary interface in response to the primary interface changing from active to at least imminently inactive status.
In general, in another aspect, the invention provides a signaling system 7 (SS7) processing system for use in an SS7 network, the system including a primary interface configured to process communications according to at least a physical-interface layer, a message transfer part 2 (MTP-2) layer and an MTP-3 layer of the SS7 protocol stack, the physical-interface layer of the primary interface being coupled to first SS7 links for conveying information between the primary interface and other portions of the SS7 network, and a backup interface configured to process communications according to the at least the physical-interface layer and the MTP-2 layer of the SS7 protocol stack, the backup interface being coupled to the primary interface to transfer data between the MTP-2 layer of the backup interface and the MTP-3 layer of the primary interface, the physical-interface layer of the backup interface being coupled to second SS7 links for conveying information between the backup interface and other portions of the SS7 network, wherein the primary and backup interfaces are configured to have the physical-layer interfaces of both the primary and backup interfaces concurrently convey information to and from the first and second SS7 links, respectively.
Implementation of the invention may include one or more of the following features. The primary and backup interfaces are configured to process communications according to the at least the physical-interface layer, the MTP-2 layer, the MTP-3 layer, an SCCP layer, an ISUP/TUP layer, and a TCAP layer of the SS7 protocol stack. The backup interface is configured to, while the primary interface is active, process information received from the second SS7 links through the MTP2 layer and convey the processed information to the MTP-3 layer of the primary interface. The primary and backup interfaces are configured such that the physical layers and MTP2 layers of both interfaces can convey information to active upper layers of the other interface.
Implementations of the invention may also include one or more of the following features. The backup interface includes a buffer, the backup interface being configured to store information received via the second SS7 links in the buffer in response to an interface-communications failure between the primary and backup interfaces via an interface link coupling the primary and backup interfaces. The backup interface is configured to provide processor-outage indicia, associated with the second SS7 links, to a signaling point in the SS7 network adjacent to the backup interface in response to the interface-communications failure. The backup interface is configured to stop providing processor-outage indicia, associated with the second SS7 links, to the signaling point in the SS7 network adjacent to the backup interface in response to the interface-communications failure ceasing. The backup interface is configured to switch to a primary mode and to stop providing processor-outage indicia, associated with the second SS7 links, to the signaling point in the SS7 network adjacent to the backup interface in response to the primary interface being at least imminently inactive.
Implementations of the invention may also include one or more of the following features. The primary and backup interfaces are disposed in a common computer chassis. The primary and backup interfaces are disposed in separate computer chassis. The backup is configured to assume processing of communications previously being processed by the primary interface in response to the primary interface changing from active to at least imminently inactive status.
In general, in another aspect, the invention provides a signaling system 7 (SS7) processing system for use in an SS7 network, the system including a primary interface configured to process communications according to at least a physical-interface layer, a message transfer part 2 (MTP-2) layer and an MTP-3 layer of the SS7 protocol stack, the physical-interface layer of the primary interface being coupled to first SS7 links for conveying information between the primary interface and other portions of the SS7 network, the primary interface being configured to provide checkpoint messages relating to the communications and the MTP-3 layer of the SS7 protocol stack, the MTP-3 layer having a corresponding MTP-3 set of information associated with each communication, the primary interface being configured to communicate with a first service application, and a backup interface configured to process communications according to the at least the physical-interface layer, the MTP-2 layer and the MTP-3 layer of the SS7 protocol stack, the backup interface being coupled to the primary interface to transfer data between the MTP-2 layer of the backup interface an the MTP-3 layer of the primary interface, the physical-interface layer of the backup interface being coupled to second SS7 links for conveying information between the backup interface and other portions of the SS7 network, the backup interface being coupled to the primary interface, and configured, to receive the checkpoint messages from the primary interface, the backup interface being configured to communicate with a second service application, wherein the primary and backup interfaces are configured to have the physical-layer interfaces of both the primary and backup interfaces concurrently convey information to and from the first and second SS7 links, respectively, and wherein the checkpoint messages contain sufficient information for the backup interface to properly process communications that are transferred from being processed by the primary interface to being processed by the backup interface and contain less than all information in each MTP-3 set of information associated with each of the communications corresponding to the MTP-3 layer of the SS7 protocol stack.
Implementations of the invention may include one or more of the following features. The primary interface and the backup interface are each configured to process communications according to signaling connection control part (SCCP), integrated services digital network user part/telephone user part (ISUP/TUP), and transaction capabilities application part (TCAP) layers of the SS7 protocol stack. The primary interface is configured to provide checkpoint messages relating to the communications and each of the SCCP, ISUP/TUP, and TCAP layers of the SS7 protocol stack, each layer having a corresponding set of information associated with each communication. The checkpoint messages contain only information sufficient for the backup interface to properly process communications, according to each layer, that are transferred from being processed by the primary interface to being processed by the backup interface.
Implementations of the invention may also include one or more of the following features. The primary and backup interfaces are disposed in a common computer chassis and the first service application is the second service application. The primary and backup interfaces are disposed in separate computer chassis and the first and second service applications are separate. The backup is configured to assume processing of communications previously being processed by the primary interface in response to the primary interface changing from active to at least imminently inactive status.
Various aspects of the invention may provide one or more of the following advantages. The invention helps provide highly-available network interfaces for telecommunications systems including switching systems, enhanced services platforms such as network voicemail systems or debit card platforms, and wireless network infrastructure such as mobile switching centers and base station controllers. Telecommunications systems can continue to operate during failures within the systems. Telecommunication systems can continue to provide services during live upgrades to the systems (e.g., upgrades to existing, currently-operating systems) and during reconfigurations. SEPs can be constructed from, and/or provided by, e.g., telecommunications equipment/service providers, one or more off-the-shelf mass-market computers while meeting 99.999% availability specifications. End users need not provision spare SS7 links, saving money on unused links and time to change links.
These and other advantages of the invention, along with the invention itself, will be more fully understood after a review of the following figures, detailed description, and claims.